The present invention relates to a joy stick, and more particularly to the joy stick in which restoring accuracy of cranks arranged in a casing has been enhanced.
An example of a related joy stick of this type will be described referring to FIGS. 9 and 10. In the drawings, a joy stick 1 is composed of a base table 2, a helical spring 3 and a spring holder 4 mounted on the base table 2 in this order, a cam 5 received in a recess 4a formed on an upper face of the spring holder 4, and an operating stick 6 attached to the cam 5 at its lower part, and a box-like casing 7 which is open at its lower face and attached to the base table 2 at its lower end part.
In the casing 7, there is disposed a lower crank 8. Shafts 8a projecting from both ends of the lower crank 8 are rotatably engaged in axial bores which are formed in a left side plate 7a and a right side plate 7b of the casing 7.
The lower crank 8 is provided in its central area with a hole 8b through which the cam 5 is adapted to be idly inserted. A pin 9 is passed through the lower crank 8 and the cam 5 so that the lower crank 8 and the cam 5 can freely pivot in a direction of an arrow X around the pin 9. Therefore, the spring holder 4 is biased upward by the helical spring 3, and accordingly, the cam 5 and the lower crank 8 are always pressed upward by the spring holder 4.
Moreover, an upper crank 10 which perpendicularly intersects the lower crank 8 is disposed in the casing 7. Shafts 10a projecting from the upper crank 10 in a direction to the back and the forth in the drawing are rotatably engaged in axial bores (not shown) which are formed in a front side plate (not shown) and a back side plate 7c of the casing 7.
In a central area of the upper crank 10, there is formed a guide groove 10b in which the operating stick 6 is idly engaged so as to be pivotable in the direction of the arrow Y. In addition, a variable resistor 11 for detecting rotation angles of the lower clank 8 is provided on an outer face of the left side plate 7a of the casing 7. A rotary shaft (not shown) of the variable resistor 11 is coupled to the left hand shaft 8a of the lower crank 8.
In the same manner, a variable resistor (not shown) for detecting rotation angles of the upper clank 10 is provided on the back side plate 7c of the casing 7, and the variable resistor is coupled to one of the shafts 10a of the upper crank 10.
In the joy stick constructed in this manner, by operating the operating stick 6 in the direction of the arrow Y, the lower crank 8 is rotated as indicated by an arrow A, and the rotation angles are detected by the variable resistor 11 thereby controlling an object to be controlled.
Similarly, by operating the operating stick 6 in the direction of the arrow X, the upper crank 10 is rotated, and the rotation angles are detected by the variable resistor. In conducting these operations, when the operating stick 6 is tilted to the left, for example, as shown in FIG. 10, the spring holder 4 is pressed by the cam 5 which rotates along with the operating stick 6, and thus, the helical spring 3 will be compressed.
When the operating stick 6 in this state is released by an operator""s finger, the operating stick 6 will be restored to a neutral position as shown in FIG. 9, along with the cam 5 by resilient restoring force of the helical spring 3. When the lower crank 8 is rotated by operating the operating stick 6 in the direction of arrow Y, the operating stick 6 will act in the same manner.
In addition to a problem of the above described joy stick 1 that the guide groove 10b of the upper crank 10 may be worn by repeated operations of the operating stick 6, but there is also a problem that the restored position of the upper crank 10 may change due to a backlash or a clearance between components in terms of accuracy, and the variable resistor 11 may not be accurately restored to the determined neutral position, resulting in inaccurate output of the control of the joy stick 1.
It is therefore an object of the present invention is to provide a joy stick which is excellent in restoring accuracy of the cranks to the neutral position and free from such confusion in the control.
In order to achieve the above object, according to the present invention, there is provided a joy stick, comprising:
an operating stick;
a first crank, which supports the operating stick so as to be pivotable in a first direction;
first flat faces, which are formed at lower both end portions in the first direction of the first crank;
a second crank, which supports the operating stick so as to be pivotable in a second direction which is perpendicular to the first direction;
second flat faces, which are formed at lower both end portions in the second direction of the second crank;
a restoration member, which is arranged coaxially with the operating stick which is situated at a neutral position thereof, the restoration member including a flat top face brought into contact with the first flat faces and the second flat faces; and
a spring member, which is arranged coaxially with the restoration member, the spring member urging the restoration member toward the first flat faces and the second flat faces.
In this configuration, the restoration member is biased upward by the spring member, thus enabling the first crank and the second crank to be accurately restored to the neutral position. Therefore, irrespective of wear of the first crank and the second crank, the restoring accuracy of the first crank and the second crank can be maintained. At the same time, the number of the components will be decreased, thus attaining a low manufacturing cost.